Pyroelectric material property considerations for x-ray generation

Abstract

The method of generating x-rays using the pyroelectric effect has garnered interest for applications that desire portability and low power consumption, particularly for real-time in-field and on-line analyses. However, the x-ray intensity produced by this type of x-ray generator is low and inconsistent compared to conventional x-ray tubes. The properties of several pyroelectric materials, including LiTaO3, LiNbO3, and PMN- xPT, were studied and subsequently tested on an in-house developed x-ray generator to explore their suitability for the application. The production of electrons to subsequently generate x-ray relies on the process of ferroelectric electron emission and field ionization to be dominant over charge compensation via the DC conductivity of the pyroelectric material. Given that the time of temperature change occurs faster than the material's charge relaxation time, it was found that the ratio of the pyroelectric coefficient to relative permittivity determined the performance of the x-ray generator. Thus, the x-ray count rates and end-point energies produced by LiTaO3 showed that it continues to be a strong candidate for such x-ray generation applications.

Features of H-=SUB=-2-=/SUB=-O adsorption on a polar surfaces of LiNbO-=SUB=-3-=/SUB=- crystals

“…In favor of this hypothesis says the fact that at a quick heating of LN and LT crystals the change in the excess screening charge on the +z surface is realized in the form of electron emission [20], which under certain conditions results in x-ray radiation [21].…”

Особенности адсорбции Н-=SUB=-2-=/SUB=-О на полярных поверхностях кристаллов LiNbO-=SUB=-3-=/SUB=-

“…Измерения проводились при V ∼ 0.1 K/min. С учетом коррекции на тепловое расширение кристалла выражение, связывающее первичный пироэлектрический коэффициент γ 1 с током I через нагрузочный резистор будет иметь такой вид [17]: Учитывая, что значения α a и α b у кристаллов НЛ конгруэнтного состава и у НЛ с примесью Mg в пределах погрешности совпадают [18,19] В пользу этого говорит то, что при быстром нагреве кристаллов НЛ и ТЛ изменение избыточного экранирующего заряда на +z поверхности реализуется в виде эмиссии электронов [20], что при определенных условиях приводит к возникновению рентгеновского излучения [21].…”

Comparative Study of Single Crystal and Polymeric Pyroelectric Detectors in the 0.9–2.0 THz Range Using Monochromatic Laser Radiation of the NovoFEL

“…The attractiveness of polymers is determined by their low cost, flexibility, mechanical and chemical resistance, and the possibility to be deposited on various types of substrates. Recent advances in pyroelectric sensor technology, comprising both single crystal and polymeric materials, include: (i) pulsed-laser detectors based on composite materials [13]; (ii) biomedical system-on-a-chip [14]; (iii) integrated sensors [15,16]; (iv) detectors for THz time-domain spectroscopy and imaging [17][18][19][20]; (v) detectors for optoacoustic microscopy [21,22]; (vi) the use of the terajet effect and Fano response to improve performance of detectors [23,24]; (vii) 3D-printed detectors [25]; (viii) X-ray generators [26], etc.…”